simple palindrome checker in C

palindrome.c

/*
 * 2016/12/12
 *
 * palindrome.c
 * Simple palindrome checker for small string. (cAsE sEnsiTivE)
 *
 * Firman Gautama <firman.gautama@gmail.com>
 *
 */
#include <stdio.h>
#include <stdlib.h> // for malloc()
#include <string.h> // for strncpy()

int isPalindrome(char *str1);

int main(void) {

  char string[] = "akuaauka";
  char result[20];

  if (isPalindrome(string) > 0) {
    strncpy(result,"Palindrome", 10);
  }
  else {
    strncpy(result,"NOT Palindrome", 14);
  }

  printf("The string: \"%s\" is %s\n", string, result);
  return 0;
}

int isPalindrome(char *str1) {

  int i=0; // real counter
  int n=0; // reverse counter
  int len = strlen(str1) - 1;

  // check for palindrome
  for(i=len;i>=0;i--) {
    printf("%c = %c\n", str1[i], str1[n]);

    // if first char is not equal last char (and the next one from each side), then exit from loop.
    if (str1[i] != str1[n]) {
      // false
      return -1;
    }
    n++;

    if (len/2 == i) {
      // if the string check went through here already, then we should break the loop because it's already in the middle of the string.
      // there is no point to continue comparing the characters because the rest of comparation should be the same.
      break;
    }
  }

  // true
  return 1;
}